Hub motor for electric bicycle

Abstract

The invention relates to a hub motor for an electric bicycle, the hub motor comprises a hub shell, a central shaft and a motor assembly, the central shaft is arranged in the hub shell in a penetrating manner, the motor assembly comprises a rotor disc rotationally arranged on the outer surface of the central shaft in a sleeving manner, the rotor disc is connected with the hub shell through a transmission mechanism, and a permanent magnet is arranged on the peripheral side of the rotor disc; a plurality of magnetic steels are uniformly arranged on the end surface at equal intervals, a stator core is fixedly arranged on the central shaft, an insulating frame is sleeved outside the stator core, a plurality of stator windings are uniformly arranged on the insulating frame along the circumferential direction, and the winding axes of the plurality of stator windings are parallel to the axis of the central shaft. The hub motor has the effects of improving the stability of a detection signal of the detection element and prolonging the service life of the hub motor.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hub motors, in particular to a hub motor for an electric bicycle. BACKGROUND

[0002] As a convenient and environmentally friendly means of transportation, electric bicycles have been widely used in short-distance travel. As the core power component of electric bicycles, the hub motor integrates the driving device in the wheel hub, eliminating intermediate transmission structures such as chains or gears, and has the advantages of high transmission efficiency and compact structure, and has become the mainstream driving scheme of modern electric bicycles.

[0003] In the prior art, the hub motor used in the electric bicycle generates a magnetic field direction between the internal stator and the rotor disc, which is usually perpendicular to the rotating shaft of the motor. In order to control the motor, a detection element is usually installed inside the motor to detect the rotor disc magnetic pole position in real time to obtain the magnetic field change signal and feedback to the controller. The common detection element is a Hall sensor.

[0004] However, the magnetic field direction perpendicular to the rotating shaft often causes unstable detection signals of the Hall sensor in actual application. Specifically, the sensitive direction of the Hall sensor is usually the axis direction of the rotating shaft, which is perpendicular to the magnetic field direction in the existing hub motor. Therefore, the actual magnetic field component detected by the Hall sensor is often smaller than the actual magnetic field strength, resulting in a low basic amplitude of the detection signal, a decreased recognition degree of subtle changes in the magnetic field, and difficulty for the Hall sensor to accurately capture the critical state of these fluctuations, which is prone to signal jumping or delay.

[0005] The above-mentioned problem of unstable detection signal of the Hall sensor directly affects the judgment of the motor rotor disc position by the control board, so that the motor is in an unstable working state for a long time, aggravating the wear of the internal components of the motor, shortening the service life of the motor, and even causing motor failure due to control error, which poses a potential threat to the safety of cycling. SUMMARY

[0006] In order to improve the stability of the detection signal of the detection element and improve the service life of the hub motor, the present application provides a hub motor for an electric bicycle.

[0007] The hub motor for an electric bicycle provided by the present application adopts the following technical scheme: A wheel hub motor for electric bicycle, comprising a wheel hub shell, a central shaft and a motor assembly, the central shaft is arranged in the wheel hub shell and rotationally matched with the wheel hub shell, the motor assembly comprises a rotor disc rotationally sleeved on the outer surface of the central shaft, the rotor disc is connected with the wheel hub shell through a transmission mechanism, the rotor disc is provided with permanent magnets on the outer circumferential side and a plurality of magnetic steels are equidistantly and uniformly arranged on the end face, the central shaft is fixedly provided with a stator core, the stator core is sleeved with an insulating frame, the insulating frame is uniformly provided with a plurality of stator windings in the circumferential direction, the winding axes of the plurality of stator windings are parallel to the central shaft axis, the wheel hub shell is provided with an MR plate electrically connected with the stator core, the MR plate is provided with a detection element, and the sensing end of the detection element faces the surface of the permanent magnet.

[0008] By adopting the above technical scheme, the stator winding is energized, since the stator winding is arranged on the stator core in the direction of the central shaft axis, at this time, the magnetic field direction generated by the magnetic steel cutting the stator winding is parallel to the direction of the central shaft axis, and the axial magnetic field is formed in cooperation with the permanent magnet, so that the magnetic field direction of the wheel hub motor is consistent with the sensitive direction of the detection element, thereby increasing the magnetic field component that can be detected by the detection element, improving the basic amplitude of the detection signal, and further improving the stability of the detection signal of the detection element and the service life of the wheel hub motor.

[0009] Optionally, the wheel hub shell is internally provided with a movement core cover, the movement core cover covers the outer circumferential side of the motor assembly, the central shaft is arranged in the movement core cover through a flat key, the movement core cover comprises a movement core cover and a movement core shell in lap joint, the stator core is detachably connected to the movement core cover through a plurality of countersunk head bolts, and the MR plate is detachably connected to the movement core cover through a connecting screw.

[0010] By adopting the above technical scheme, the movement core cover protects the internal motor assembly, reduces the intrusion of external impurities on the motor assembly, thereby prolonging the service life of the whole motor, and the stator core and the MR plate are detachably connected to the movement core cover, so that workers can conveniently maintain and replace the motor assembly, thereby reducing the maintenance cost and difficulty.

[0011] Optionally, the transmission mechanism comprises an inner ring gear, a primary reduction assembly and a secondary reduction assembly, the inner ring gear is fixedly arranged in the movement core shell, the power input end of the primary reduction assembly is connected with the rotor disc, the power output end is connected with the power input end of the secondary reduction assembly, and the power output end of the secondary reduction assembly is connected with the wheel hub shell.

[0012] By adopting the technical scheme, the stator winding drives the rotation of the rotor disc after being electrified, at this time, the primary reduction assembly reduces the high-speed rotation of the rotor disc and then drives the secondary reduction assembly, and then the secondary reduction assembly reduces the power again and drives the wheel hub shell, so that a larger transmission ratio is formed between the rotor disc and the wheel hub shell, thereby increasing the output torque of the wheel hub shell, and meeting the power demand of the electric bicycle for low speed and high torque.

[0013] Optionally, the primary reduction assembly comprises a primary sun gear base, a primary sun gear and a primary planet carrier, the primary sun gear base is coaxially arranged with the rotor disc, the primary planet carrier is provided with a plurality of primary planet gears, the plurality of primary planet gears are located between the primary sun gear and the tooth surface of the inner ring gear and simultaneously meshed with the primary sun gear and the inner ring gear; the secondary reduction assembly comprises a secondary sun gear, a secondary planet carrier and an output ring, the secondary sun gear is meshed with the inner tooth surface of the primary planet carrier, the secondary planet carrier is provided with a plurality of secondary planet gears, the plurality of secondary planet gears are located between the secondary sun gear and the tooth surface of the inner ring gear and simultaneously meshed with the secondary sun gear and the inner ring gear, the output ring is rotatably sleeved on the central shaft, and the secondary planet carrier and the wheel hub shell are connected with the output ring.

[0014] By adopting the technical scheme, the rotor disc drives the rotation of the primary sun gear base when rotating, the primary sun gear base drives the rotation of the primary sun gear, thereby driving the plurality of primary planet gears to rotate around the axis of the primary planet gears while doing revolution along the tooth surface of the inner ring gear, the revolution of the primary planet gears drives the synchronous rotation of the primary planet carrier, the primary planet carrier drives the rotation of the secondary sun gear, the rotation of the secondary sun gear drives the plurality of secondary planet gears to rotate while doing revolution along the tooth surface of the inner ring gear, thereby driving the synchronous rotation of the secondary planet carrier, and the secondary planet carrier drives the rotation of the wheel hub shell through the output ring.

[0015] Optionally, a ventilation groove is formed in the central shaft and extends to the inside of the wheel hub shell, a plurality of air inlet holes are uniformly formed in the circumference of the core cover, a partition plate is arranged in the core shell, a plurality of air inlet openings are uniformly formed in the circumference of the partition plate, an air inlet groove is formed in the core shell and communicates with the air inlet openings, and a plurality of air outlet holes are formed in the side of the wheel hub shell close to the core cover.

[0016] By adopting the technical scheme, in the process of operation of the hub motor, external air enters the inside of the hub shell through the ventilation groove, flows through the surface of the motor assembly, and forms hot air after absorbing heat, and then the hot air flows into the gap between the outer surface of the core shell and the inner side wall of the hub shell through the multiple air inlets and the multiple air inlets, and finally is discharged through the multiple air outlets, so that the motor assembly inside the core shell is effectively cooled, the possibility of performance degradation or component damage of the motor caused by high temperature is reduced, and the service life of the motor is prolonged.

[0017] Optionally, a plurality of accommodating grooves are formed in the rotor disc, the accommodating grooves are parallel to the radial direction of the rotor disc, each of the accommodating grooves is slidably connected with a cooling fin, and a tension spring is arranged in the accommodating groove and provides a force opposite to the centrifugal force acting on the cooling fin.

[0018] By adopting the technical scheme, when the rotor disc rotates, the cooling fin has a tendency to slide outward under the action of the centrifugal force, and the tension spring provides a counteracting force to balance the cooling fin, so that the extension length of the cooling fin dynamically changes with the rotation speed of the rotor disc, when the rotation speed increases, the centrifugal force acting on the cooling fin is greater than the elastic force of the tension spring, the cooling fin extends out of the accommodating groove, and the contact area between the rotor disc and air is increased to improve the convective heat dissipation efficiency; when the rotation speed decreases, the tension spring pulls the cooling fin back to reduce the wind resistance and reduce the energy consumption.

[0019] Optionally, the plurality of accommodating grooves are distributed in a spiral line along the axis direction of the rotor disc.

[0020] By adopting the technical scheme, when the rotor disc rotates, the spiral cooling fin can guide the airflow to flow along the spiral track, thereby increasing the contact time and contact area of the airflow and the cooling fin, and can also promote the air to form directional circulation in the axial direction of the rotor disc, so that the hot air flows out through the air inlets and the air inlets more quickly, and the convective heat dissipation efficiency is further improved.

[0021] Optionally, a limiting groove is formed in the inner side wall of the accommodating groove, a rotating block is rotatably connected to the cooling fin, and the rotating block is rollingly arranged in the limiting groove, when the rotating block abuts against the end of the limiting groove away from the central shaft, a gap is left between the cooling fin and the inner side wall of the core shell.

[0022] By adopting the technical scheme, the length of the limiting groove controls the maximum extension amount of the cooling fin, and ensures that the cooling fin and the inner side wall of the core shell always leave a gap, so that heat is generated by friction between the cooling fin and the core shell is avoided, and the heat dissipation burden of the inside of the core shell is reduced.

[0023] In summary, the present application has at least one of the following beneficial technical effects: 1. The application is to parallel the axis of the stator winding to the center axis, because the stator winding is wound on the stator core in the direction of the center axis, and the magnetic field generated by the magnetic steel cutting the stator winding is parallel to the direction of the center axis, which cooperates with the permanent magnet to form an axial magnetic field, so that the magnetic field direction of the wheel hub motor is consistent with the sensitive direction of the detection element, thereby increasing the magnetic field component that the detection element can detect, improving the basic amplitude of the detection signal, and further improving the stability of the detection signal of the detection element and the service life of the wheel hub motor. 2. The application connects the wheel hub shell and the rotor disc through the transmission mechanism, which transmits power to the wheel hub shell through secondary speed reduction, so that a larger transmission ratio is formed between the rotor disc and the wheel hub shell, thereby increasing the output torque of the wheel hub shell to meet the power demand of electric bicycles for low speed and high torque. 3. The application is to open a ventilation slot, an air inlet hole, an air inlet, an air inlet slot and an air outlet hole. External air enters the inside of the wheel hub shell through the ventilation slot, flows through the surface of the motor assembly, and forms hot air after absorbing heat. Then the hot air flows into the gap between the outer surface of the core shell and the inner side wall of the wheel hub shell through multiple air inlets and multiple air inlets, and is finally discharged through multiple air outlets, thereby achieving effective heat dissipation of the motor assembly inside the core cover.

[0024] 4. The application is to set up a tension spring and a cooling fin. When the rotor disc rotates, the cooling fin has a tendency to slide outward under the action of centrifugal force, and the tension spring provides a counteracting force to balance, so that the extension length of the cooling fin changes dynamically with the rotor disc speed. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a structural schematic diagram of embodiment 1 of the application.

[0026] Figure 2 is a cross-sectional view of the wheel hub shell in embodiment 1 of the application.

[0027] Figure 3 is a cross-sectional view of the stator core and the rotor disc in embodiment 1 of the application.

[0028] Figure 4 is an exploded schematic diagram of the primary speed reduction assembly and the secondary speed reduction assembly in embodiment 1 of the application.

[0029] Figure 5 is a structural schematic diagram of embodiment 2 of the application.

[0030] Figure 6 is a structural schematic diagram of the core cover in embodiment 2 of the application.

[0031] Figure 7 is a cross-sectional view of the rotor disc in embodiment 2 of the application.

[0032] Figure 8 is the application Figure 7 A zoomed-in view of the area marked A in the figure.

[0033] BRIEF DESCRIPTION OF DRAWINGS: 1, hub shell; 2, center shaft; 21, ventilation groove; 101, tower base; 102, disc brake end cover; 103, air outlet hole; 3, core cover; 31, core cover; 311, air inlet hole; 32, core shell; 321, air inlet groove; 33, partition; 331, air inlet; 4, motor assembly; 41, stator core; 42, insulation frame; 43, rotor disc; 44, permanent magnet; 45, magnetic steel; 46, MR board; 5, transmission mechanism; 51, inner ring gear; 52, first-stage reduction assembly; 521, first-stage sun gear base; 522, first-stage sun gear; 523, first-stage planet carrier; 524, first-stage planet gear; 53, second-stage reduction assembly; 531, second-stage sun gear; 532, second-stage planet carrier; 533, output ring; 534, second-stage planet gear; 6, containing groove; 61, limiting groove; 7, cooling fin; 8, tension spring; 71, rotating wheel. DETAILED DESCRIPTION

[0034] The following will be described in detail in combination with the Figures 1-8 application.

[0035] Example 1 The embodiments of the application disclose a hub motor for an electric bicycle.

[0036] Referring to Figure 1 , a hub motor for an electric bicycle comprises a hub shell 1, a center shaft 2 is provided inside the hub shell 1 to provide a mounting reference, the center shaft 2 is rotationally connected with the hub shell 1, one end of the hub shell 1 is fixedly connected with a tower base 101, the tower base 101 is rotationally connected on the center shaft 2 through a bearing, a chain wheel adapted to a chain can be arranged on the tower base 101, so that the vehicle can be driven to rotate the chain wheel and the tower base 101 through the chain by pedaling, and then the hub shell 1 is driven to rotate by the tower base 101.

[0037] Referring to Figure 1 , a disc brake end cover 102 is sealingly and fixedly installed on the side end face of the hub shell 1 away from the tower base 101 by bolts, so that the disc brake can brake the wheel on which the disc brake is installed.

[0038] Referring to Figure 1 and Figure 2The hub shell 1 is internally provided with a movement cover 3, the central shaft 2 is arranged in the movement cover 3 through a flat key, the movement cover 3 comprises a movement cover 31 and a movement shell 32 which are overlapped and matched, the movement cover 3 is internally provided with a motor assembly 4, the movement cover 3 protects the motor assembly 4 inside, reduces the invasion of external impurities to the motor assembly 4, and thus prolongs the service life of the motor as a whole.

[0039] With reference to Figure 1 and Figure 2 , the motor assembly 4 comprises a stator core 41 which is detachably connected to the end face of the movement cover 31 towards the movement shell 32 through a plurality of countersunk head bolts, the stator core 41 is sleeved on the surface of the central shaft 2, and an insulating frame 42 is sleeved on the outer surface of the stator core 41, a plurality of stator windings (not shown in the figure) are uniformly distributed on the insulating frame 42 in the circumferential direction, and the number of stator windings is twelve in this embodiment, and the winding axis of each stator winding is parallel to the axis of the central shaft 2.

[0040] With reference to Figure 2 and Figure 3 , the outer surface of the central shaft 2 is rotatably connected with a rotor disc 43 through a bearing, the rotor disc 43 is sleeved on the outer surface of the central shaft 2 and is arranged on the side of the stator core 41 away from the movement cover 31, the rotor disc 43 is integrally formed with a protruding portion, the protruding portion is fixedly installed with a permanent magnet 44 composed of seven pairs of magnetic poles, and the surface of the rotor disc 43 is uniformly connected with a plurality of magnetic steels 45 in the circumferential direction, and the number of magnetic steels 45 is fourteen in this embodiment, and the surface of the rotor disc 43 away from the stator core 41 is connected with the hub shell 1 through a transmission mechanism 5.

[0041] With reference to Figure 2 and Figure 3 , the end face of the movement cover 31 towards the stator core 41 is fixedly installed with an MR board 46 electrically connected with the stator core 41 through a plurality of connecting screws, so that the MR board 46 is convenient to replace and maintain, a detection element (not shown in the figure) is installed on the MR board 46, and the sensing end of the detection element faces the surface of the permanent magnet 44, and the detection element is a Hall sensor in this embodiment, and the sensitive direction of the detection element is parallel to the axis of the central shaft 2.

[0042] The stator windings are energized through the power supply device, since the stator windings are wound on the stator core 41 in the direction of the axis of the central shaft 2, at this time, the magnetic field direction generated by the magnetic steels 45 cutting the stator windings is parallel to the direction of the axis of the central shaft 2, and the axial magnetic field is formed in cooperation with the permanent magnet 44, so that the magnetic field direction of the hub motor is consistent with the sensitive direction of the detection element, thereby increasing the magnetic field component that can be detected by the detection element, improving the basic amplitude of the detection signal, and further improving the stability of the detection signal of the detection element and the service life of the hub motor.

[0043] With reference to Figure 2 andFigure 4 The inner side of the movement shell 32 is fixedly connected with a partition plate 33, and the motor assembly 4 and the transmission mechanism 5 are arranged on the two sides of the partition plate 33 respectively. The transmission mechanism 5 comprises an inner gear ring 51, a primary reduction assembly 52 and a secondary reduction assembly 53. The inner gear ring 51 is fixedly connected to the inner side wall of the movement shell 32 and is coaxially arranged with the central shaft 2. The power input end of the primary reduction assembly 52 is connected with the rotor disc 43, the power output end is connected with the power input end of the secondary reduction assembly 53, and the power output end of the secondary reduction assembly 53 is connected with the hub shell 1.

[0044] With reference to Figure 2 and Figure 4 Specifically, the primary reduction assembly 52 comprises a primary sun gear base 521, a primary sun gear 522 and a primary planet carrier 523 which are sleeved on the outer surface of the central shaft 2. The primary sun gear base 521 is fixedly installed on the rotor disc 43 by three bolts. The inner tooth surface of the primary sun gear base 521 is engaged with the primary sun gear 522. The primary planet carrier 523 is rotatably connected to the outer surface of the central shaft 2 by a bearing. Four primary planet gears 524 are rotatably connected to the primary planet carrier 523. The four primary planet gears 524 are located between the tooth surface of the primary sun gear 522 and the inner gear ring 51 and are engaged with the primary sun gear 522 and the inner gear ring 51 at the same time.

[0045] With reference to Figure 2 and Figure 4 The secondary reduction assembly 53 comprises a secondary sun gear 531, a secondary planet carrier 532 and an output ring 533 which are sleeved on the outer surface of the central shaft 2. The secondary sun gear 531 is engaged with the inner tooth surface of the primary planet carrier 523. The secondary planet carrier 532 is rotatably connected to the outer surface of the central shaft 2 by a bearing. Four secondary planet gears 534 are rotatably connected to the secondary planet carrier 532. The four secondary planet gears 534 are located between the tooth surface of the secondary sun gear 531 and the inner gear ring 51 and are engaged with the secondary sun gear 531 and the inner gear ring 51 at the same time. The output ring 533 is fixedly sleeved on the outer surface of the secondary planet carrier 532. The end face of the output ring 533 away from the secondary planet carrier 532 is connected with the inner side wall of the hub shell 1.

[0046] The power supply device is powered on to the stator winding, and the electromagnetic induction generated by the stator winding and the magnetic steel 45 drives the rotation of the rotor disc 43. When the rotor disc 43 rotates, it drives the rotation of the first sun gear base 521, and the first sun gear base 521 drives the rotation of the first sun gear 522, thereby driving the four first planetary gears 524 to rotate around their own axes while performing a revolution along the inner ring gear 51 tooth surface. The revolution of the four first planetary gears 524 drives the first planetary carrier 523 to rotate synchronously, and the first planetary carrier 523 drives the second sun gear 531 to rotate, which drives the multiple second planetary gears 534 to rotate while revolving along the inner ring gear 51 tooth surface, thereby driving the second planetary carrier 532 to rotate synchronously. The second planetary carrier 532 drives the wheel hub shell 1 to rotate through the output ring 533, thereby achieving power transmission from the rotor disc 43 to the wheel hub shell 1. At the same time, the power is reduced twice through the first reduction assembly 52 and the second reduction assembly 53, thereby forming a large transmission ratio between the rotor disc 43 and the wheel hub shell 1, and increasing the output torque of the wheel hub shell 1 to meet the power demand of the electric bicycle for low speed and high torque.

[0047] The implementation principle of the wheel hub motor for the electric bicycle according to the embodiment of the application is as follows: the power supply device is powered on to the stator winding, and the electromagnetic induction generated by the stator winding and the magnetic steel 45 drives the rotation of the rotor disc 43. The rotor disc 43 drives the rotation of the wheel hub shell 1 through the transmission mechanism 5. In the process of generating a magnetic field, the stator winding is arranged on the stator core 41 in the direction of the central axis 2 axis. At this time, the magnetic field generated by the magnetic steel 45 cutting the stator winding is parallel to the direction of the central axis 2 axis, and cooperates with the permanent magnet 44 to form an axial magnetic field, so that the direction of the magnetic field of the wheel hub motor is consistent with the sensitive direction of the detection element, thereby increasing the magnetic field component that can be detected by the detection element, improving the basic amplitude of the detection signal, and further improving the stability of the detection signal of the detection element and the service life of the wheel hub motor.

[0048] Embodiment 2 With reference to Figure 5 and Figure 6 The difference between the embodiment of the application and the embodiment 1 is that the central axis 2 is provided with a ventilation groove 21 near the side of the disc brake end cover 102 along the axis direction, the ventilation groove 21 extends to the inside of the wheel hub shell 1, and a plurality of air inlet holes 311 are uniformly arranged on the machine core cover 31 in the circumferential direction. In this embodiment, the number of air inlet holes 311 is three.

[0049] With reference to Figure 6 and Figure 7The plurality of air inlets 331 are evenly arranged on the outer circumferential side of the inner side wall of the core shell 32. The plurality of air inlets 331 are in communication with the air inlet groove 321. The air inlet groove 321 is in communication with the gap between the inner side wall of the hub shell 1 and the outer side wall of the core shell 32. The plurality of air outlets 103 are arranged on the side of the hub shell 1 close to the disc brake end cover 102. The plurality of air outlets 103 are evenly distributed along the outer circumferential side of the hub shell 1.

[0050] With reference to Figure 7 During the operation of the hub motor, the external air enters the hub shell 1 through the air inlet groove 21, and then enters the core cover 3 through the air inlet hole 311. The air absorbs heat from the surface of the motor assembly 4 in the core cover 3 to form hot air. Then the hot air flows into the gap between the outer side wall of the core shell 32 and the inner side wall of the hub shell 1 through the plurality of air inlets 331 and the air inlet groove 321, and finally is discharged through the plurality of air outlets 103. In this way, the motor assembly 4 in the core cover 3 is effectively cooled, reducing the possibility of performance degradation or component damage of the motor due to high temperature, thereby prolonging the service life of the motor.

[0051] With reference to Figure 7 and Figure 8 In order to improve the efficiency of convective heat dissipation, a plurality of accommodating grooves 6 are arranged on the outer circumferential end surface of the rotor disc 43. The length of the accommodating groove 6 is parallel to the radial direction of the rotor disc 43. The plurality of accommodating grooves 6 are arranged in a spiral line along the axis direction of the rotor disc 43. A heat sink 7 and a tension spring 8 are arranged in each accommodating groove 6. The heat sink 7 is slidingly connected in the accommodating groove 6. One end of the tension spring 8 is fixedly connected to the inner side wall of the accommodating groove 6 close to the axis direction of the central shaft 2. The other end of the tension spring 8 is fixedly connected to the heat sink 7. The force of the tension spring 8 acting on the heat sink 7 is opposite to the centrifugal force acting on the heat sink 7.

[0052] When the rotor disc 43 rotates, the heat sink 7 has a tendency to slide outward under the action of centrifugal force. When the rotational speed increases, the centrifugal force acting on the heat sink 7 is greater than the elastic force of the tension spring 8. The heat sink 7 extends out of the accommodating groove 6 and is arranged in a spiral line on the outer surface of the rotor disc 43. At this time, the plurality of rotating heat sinks 7 guide the airflow to flow along the spiral trajectory, push the air to form directional circulation in the axial direction of the rotor disc 43, and accelerate the hot air to flow out through the air inlet 331 and the air inlet groove 321, thereby further improving the efficiency of convective heat dissipation. When the rotational speed decreases, the tension spring 8 pulls the heat sink 7 back to reduce the air resistance and reduce energy consumption.

[0053] With reference to Figure 7 and Figure 8The limiting groove 61 is arranged on the inner side wall of the accommodating groove 6, and the opposite ends of the heat dissipation fin 7 are rotationally connected with rotating blocks, the rotating blocks are rollingly connected in the limiting groove 61, the rotating blocks change the sliding friction into rolling friction, the friction when the heat dissipation fin 7 slides is reduced, so that the heat generated by the friction is reduced, when the centrifugal force pushes the rotating blocks to move to the end of the limiting groove 61 far from the central shaft 2, the gap is left between the heat dissipation fin 7 and the inner side wall of the movement core shell 32, the maximum extension of the heat dissipation fin 7 is controlled through the limiting groove 61, the gap is ensured between the heat dissipation fin 7 and the inner side wall of the movement core shell 32, so that the heat generated by the friction between the heat dissipation fin 7 and the movement core shell 32 is avoided.

[0054] The principle of the embodiment 2 is that: in the process of the operation of the wheel hub motor, the external air enters the inside of the wheel hub shell 1 through the ventilation groove 21, then the air enters the inside of the movement core cover 3 through the air inlet hole 311, the air absorbs the heat on the surface of the motor assembly 4 to form hot air when flowing in the movement core cover 3, then the hot air flows into the gap between the outer side wall of the movement core shell 32 and the inner side wall of the wheel hub shell 1 through the multiple air guide holes 331 and the air guide groove 321, and finally is discharged through the multiple air outlet holes 103, so that the effective heat dissipation of the motor assembly 4 in the inside of the movement core cover 3 is realized, the possibility of the performance attenuation or the component damage of the motor caused by the high temperature is reduced, so that the service life of the motor is prolonged.

[0055] The above are the preferred embodiments of the application, not the limitation of the protection scope of the application, so that: all the equivalent changes made according to the structure, shape, principle of the application should be covered in the protection scope of the application.

Claims

1. A wheel hub motor for an electric bicycle, characterized by, The application relates to a wheel hub motor, which comprises a wheel hub shell (1), a central shaft (2) and a motor assembly (4), the central shaft (2) is arranged in the wheel hub shell (1) and rotationally matched with the wheel hub shell (1), the motor assembly (4) comprises a rotor disc (43) rotationally arranged on the outer surface of the central shaft (2), the rotor disc (43) is connected with the wheel hub shell (1) through a transmission mechanism (5), the rotor disc (43) is provided with permanent magnets (44) on the outer circumferential side, and a plurality of magnetic steels (45) are equidistantly and uniformly arranged on the end face, a stator core (41) is fixedly arranged on the central shaft (2), an insulating frame (42) is arranged on the stator core (41), a plurality of stator windings are uniformly arranged on the insulating frame (42) in the circumferential direction, the winding axes of the plurality of stator windings are parallel to the axis of the central shaft (2), an MR plate (46) electrically connected with the stator core (41) is arranged in the wheel hub shell (1), a detection element is arranged on the MR plate (46), and the inductive end of the detection element faces the surface of the permanent magnet (44).

2. A wheel hub motor for an electrically powered bicycle according to claim 1, characterized in that A movement core cover (3) is arranged in the wheel hub shell (1), the movement core cover (3) covers the outer circumferential side of the motor assembly (4), the central shaft (2) is arranged in the movement core cover (3) through a flat key, the movement core cover (3) comprises a movement core cover (31) and a movement core shell (32) in overlap matching mode, the stator core (41) is detachably connected to the movement core cover (31) through a plurality of countersunk head bolts, and the MR plate (46) is detachably connected to the movement core cover (31) through a connecting screw.

3. A wheel hub motor for an electrically powered bicycle according to claim 2, characterized in that The transmission mechanism (5) comprises an inner gear ring (51), a primary reduction assembly (52) and a secondary reduction assembly (53), the inner gear ring (51) is fixedly arranged in the movement core shell (32), the power input end of the primary reduction assembly (52) is connected with the rotor disc (43), the power output end is connected with the power input end of the secondary reduction assembly (53), and the power output end of the secondary reduction assembly (53) is connected with the wheel hub shell (1).

4. A wheel hub motor for an electrically powered bicycle according to claim 3, characterized in that The primary reduction assembly (52) comprises a primary sun gear base (521), a primary sun gear (522) and a primary planet carrier (523), the primary sun gear base (521) is coaxially arranged with the rotor disc (43), the primary sun gear base (521) is arranged in meshing with the primary sun gear (522), a plurality of primary planet gears (524) are arranged on the primary planet carrier (523), and the plurality of primary planet gears (524) are located between the primary sun gear (522) and the tooth surface of the inner ring gear (51) and are in meshing with the primary sun gear (522) and the inner ring gear (51); the secondary reduction assembly (53) comprises a secondary sun gear (531), a secondary planet carrier (532) and an output ring (533), the secondary sun gear (531) is in meshing with the inner tooth surface of the primary planet carrier (523), a plurality of secondary planet gears (534) are arranged on the secondary planet carrier (532), the plurality of secondary planet gears (534) are located between the secondary sun gear (531) and the tooth surface of the inner ring gear (51) and are in meshing with the secondary sun gear (531) and the inner ring gear (51), and the output ring (533) is rotatably arranged on the central shaft (2), and the secondary planet carrier (532) and the hub shell (1) are connected with the output ring (533).

5. A wheel hub motor for an electrically powered bicycle according to claim 2, wherein, Ventilation grooves (21) are formed in the central shaft (2), the ventilation grooves (21) extend into the hub shell (1), a plurality of air inlet holes (311) are uniformly formed in the circumference of the core cover (31), a partition plate (33) is arranged in the core shell (32), a plurality of air guide holes (331) are uniformly formed in the circumference of the partition plate (33), air guide grooves (321) are formed in the core shell (32) and communicate with the air guide holes (331), and a plurality of air outlet holes (103) are formed in the side of the hub shell (1) close to the core cover (31).

6. A wheel hub motor for an electrically powered bicycle according to claim 5, characterized in that A plurality of accommodating grooves (6) are formed in the rotor disc (43), the accommodating grooves (6) are parallel to the radial direction of the rotor disc (43), a heat dissipation fin (7) is slidably connected in each accommodating groove (6), a tension spring (8) is arranged in the accommodating groove (6), and the force of the tension spring (8) on the heat dissipation fin (7) is opposite to the direction of the centrifugal force acting on the heat dissipation fin (7).

7. A wheel hub motor for an electrically powered bicycle according to claim 6, characterized in that The plurality of accommodating grooves (6) are distributed in a spiral line along the axial direction of the rotor disc (43).

8. A wheel hub motor for an electrically powered bicycle according to claim 6, wherein, A limiting groove (61) is formed in the inner side wall of the accommodating groove (6), a rotating block is rotatably connected to the heat dissipation fin (7), the rotating block is rollingly arranged in the limiting groove (61), and when the rotating block abuts against the end of the limiting groove (61) away from the central shaft (2), a gap is left between the heat dissipation fin (7) and the inner side wall of the core shell (32).

Images